Construction of earthen fills

ABSTRACT

A method for construction of earthen fills that comprises use of actual, cumulative field compaction energy generated by soil compactors as a function of rolling resistance with soil densification, to determine the asymptotic energy-density approach range.

RELATED APPLICATIONS

This application is a continuation in part of co-pending applicationSer. No. 12/930,391 filed Jan. 4, 2011, which is a continuation in partof co-pending application Ser. No. 11/522,701 filed Sep. 18, 2006, whichis a continuation in part of application Ser. No. 10/924,132 filed Aug.23, 2004, now U.S. Pat. No. 7,110,884; which is a continuation of Ser.No. 10/244,998 filed Sep. 16, 2002, now U.S. Pat. No. 6,859,732 which isa section 371 national phase application from PCT Internationalapplication Number PCT/US01/15638 Filed 15 May 2001.

TECHNICAL FIELD

This invention encompasses new methods for and in earthen fillengineering and construction and includes application to all soils,treated and amended soils, and earthen base and sub-base materials. Theprior related applications listed above were focused on the engineeringaspects of the invention—in this application we turn to the constructionapplications of the invention. More specifically this invention involvesnew methods to use actual, cumulative field compaction energy generatedby soil compactors as a function of rolling resistance with soildensification, to determine the asymptotic energy-density approach rangeand associated compaction performance, and tie or correlate theasymptotic compaction performance to compacted engineering properties,moisture-density relations and the end point of lift compaction.

BACKGROUND OF THE INVENTION

In current engineering practice, the specification and control ofdensity and moisture of earthen fill is typically based on the resultsof the Standard Proctor compaction test (American Society for TestingMaterials [ASTM] D698) or the Modified Proctor compaction test (ASTMD1557), or other similar test standards derived from the Proctor testsand established by other institutes and governments (i.e. AASHTO, etc.).All standard tests used in practice utilize fixed soil compactionenergies. The compaction energy used in the Standard Proctor compactiontest is 600 kilonewton-meter per cubic meter Kn-m/m³ or 12,400 footpounds per cubic foot (ft-lbs/cf). The other standard tests based on theStandard Proctor Test use the same or comparable fixed energy levels.These standard tests are based on work by R. R. Proctor, who estimatedthe field compaction energies of two predominant, towed compactors (orrollers) used in the early 1930's. These fixed compaction energy levelswere based on drawbar pull values measured on the towed compactors, andconsidered to be somewhat representative of field compaction energies.Subsequently, it was found that many structural fills constructed byusing the standard proctor energy were failing over time. Thesecircumstances led to the development of a larger towed roller which ledto the development of the Modified Proctor compaction test (ASTM D 1557)by R. R. Proctor to simulate the compaction energy of the larger roller.Hunt, R. E. (1986) Geotechnical Engineering Analysis and Evaluation,McGraw-Hill Book Co., p. 211. The compaction energy used in ASTM D1557(2,700 Kn-m/m³, or 56,000 ft-lbs/cf) is about 4.5 times higher than thecompaction energy used in ASTM D698. Even in the 1930's and 1940's itwas recognized that the laboratory compaction tests produced energiesthat were inconsistent with field compaction energies. Numerous attemptswere made to develop test procedures that produced field and laboratorycompaction (moisture-density) curves that would be more comparable. Thepresent inventors have published a very basic approach to improvedprocedures: 1.) “Practice Improvements for the Design and Constructionof Earth Fills”, Proceedings of the Eighth Annual Conference onContaminated Soils”, University of Massechusetts at Amherst, 1994; andGeoenvironment 2000 Conference, New Orleans, La., 1995; and 2.)“Practice Improvements for the Design and Construction of Earth Fills”,Proceedings of the Texas Section Fall Meeting, 1995, American Society ofCivil Engineers, El Paso, Tex. There has not previously been availablein the art practicable methods to derive actual cumulative fieldcompaction energies unique to each site construction lift based onsoil/compactor/lift thickness/moisture/soil amendment combinations,actual compaction performance including moisture-density relations andengineering properties based on the same unique soil/compactor/liftthickness/moisture/soil amendment combinations, a data matrix developedto provide actual field combination-specific compaction energy levelsand engineering property correlations based on variablesoil/compactor/moisture/lift thickness combinations, or to allowextrapolation for intermediate combinations or compaction conditions,with or without field data, or to select field-specific compactionenergy levels to be applied in laboratory tests or utilized inengineering methods, rather than the fixed energies of the standard testmethods described above. The new improvements provide a different methodfor modeling of actual, combination-specific field compaction energiesin the laboratory that are not fixed, and provide for designapplications and specifications, and construction, for all types ofcompactors combined with all classes of earthen fills moisture states,lift thickness,' and soil amendments.

SUMMARY OF THE INVENTION

The invention provides a method for construction of earthen fills thatcomprises use of actual, cumulative field compaction energy generated bysoil compactors as a function of rolling resistance with soildensification, to determine the asymptotic energy-density approach rangeand associated asymptotic compaction performance. Another preferredembodiment correlates the asymptotic compaction performance to one ormore values selected from the group consisting of moisture-densityrelations, optimum moisture-density, percentages of maximum dry-densitycompaction, the compactor make and model, soil properties, compactorperformance, compactor-soil interface, and the end point of liftcompaction. In another preferred embodiment any drive train step orcomponent of compactor performance resulting in rimpull driveperformance or drive power, including compactor horsepower is isolatedor measured to establish change in rimpull performance with rollingresistance. For example rimpull rolling resistance is measured byrimpull power performance which is the drive power of the compactor atthe wheel where the compactor is mobilized. For a particular lift,compaction is deemed complete when the change in rimpull rollingresistance falls below a value considered insignificant. One measure ofinsignificant change where compaction is deemed complete is when themeasured change in rolling resistance is less than the measured errorfor determining rolling resistance. In an especially preferredembodiment a drive train step or component of engine power performanceis tracked or measured and transmitted to a computation means to trackvariation of power performance for each pass over a given area to becompacted, and the compactor operator receives an instruction when thedesired magnitude of the change in engine power is achieved. The methodmay include a real time computation of change in rolling resistance usedto identify the asymptotic energy-density approach range. The method mayalso include providing means for drive train power or energy data as ameasure of rimpull energy to be transmitted to a receiving station andthe transmitted data is used to compute the asymptotic energy densityapproach range. Alternatively the invention can be defined as a methodfor construction of earthen fills that comprises determining fieldspecific rolling resistance at the asymptotic energy-density approachand associated asymptotic compaction performance and correlating thedetermined rolling resistance to engineering properties of the compactedlift. In a preferred embodiment the engineering properties of thecompacted lift is the end point for compaction. An alternative method ofthe invention provides a method for compaction of earthen fills thatcomprises determining field measured, site specific rimpull rollingresistance changes until the magnitude of change in rimpull rollingresistance indicates the asymptotic energy-density approach range hasbeen reached for the area being compacted. A preferred method useschanges in rimpull rolling resistance measured by changes in compactorpower performance.

The invention defined in this application provides for a differentmethod for determining compaction energy and associatedmoisture-density/engineering property relations in the asymptoticenergy-density approach range with compactor passes for any givencombination of soil type, soil properties, compactor, moisture content,lift thickness, and soil amendment, based on energy from the compactorspower source and drive train—including a vibratory or impact energycomponent that may be added in the case of dynamic or vibratorycompactors, and determining cumulative, field/lift-specific compactionenergy as a function of rolling resistance. The invention also includesrelating soil lift compaction performance, moisture-density relationsand compacted engineering properties, in relation to the properties ofthe lift soil and the soil/compactor interface. The method includestracking energy distribution from the compactor and into the soil. Themethod provides asymptotic compaction performance in the asymptoticenergy-density approach range correlated to any stage, measure orcomponent of energy distribution and/or transmission from the compactorspower source to the cumulative, field/lift-specific compaction energy inconstruction. The method provides measuring or monitoring of cumulativerolling resistance, compaction energy, compactive energy loss,compaction performance and engineering properties of the compacted liftat asymptotic compaction performance, under practical and controlledconstruction conditions. The method includes determining or monitoringthe unit cumulative compactive energy per unit volume at asymptoticcompaction performance in the asymptotic energy-density approach rangefor each compactor pass by using the cumulative average rollingresistance. The invention provides a method for establishing engineeringquality control and quality assurance in construction and determiningactual, cumulative field compaction energy and associated engineeringproperty relationships for a given soil. The improvement in the methodincludes for a selected compactor, measuring, monitoring or determiningthe energy transferred to the soil by measuring or monitoring rollingresistance or change in rolling resistance as a function of rimpull ordrive energy performance, plotting the variation of rolling resistancefor a plurality of roller passes, determining the site-specific,asymptotic energy-density approach range, determining the cumulativeaverage rolling resistance at asymptotic compaction performance withinsaid asymptotic energy-density approach range, and determining when fulllift compaction performance, the end point of lift compaction, or designenergy levels are met or exceeded. Alternative measurements andrelations include correlations with horsepower or any stage, measure orcomponent of the source compactor energy or power train. The method alsoincludes additional forces that may be applied to the soil by vibratoryor other dynamic forces from compactors. Optionally the invention maycomprise the steps of 1) tracking energy distribution and isolatingcompaction energy transfer, 2) determining cumulative site lift-specificcompaction energy and corresponding engineering properties or monitoringsite-lift specific compaction energy variation and correspondingengineering properties for a soil type, a compactor type, and at leastone additional variable selected from the group consisting of moisturecontent, lift thickness, and soil amendments. preferably measuring ormonitoring compaction energy or rolling resistance variation for aplurality of roller passes, measuring or monitoring compaction energy orrolling resistance variation with dry density variation for a pluralityof roller passes, and more preferably measuring compaction energychanges including dynamic or vibratory energy in variation with drydensity for a plurality of roller passes. The method may optionallymeasure at least one additional variable selected from the groupconsisting of lift thicknesses, soil moisture contents, soil types, andsoil amendment, The method may include field measurements that are usedto establish specific and corresponding parabolic curves of compactionenergy including dynamic or vibratory energy components versus soilmoisture-density relations and optionally further comprises determiningthe unit cumulative compaction energy per unit volume within theasymptotic energy-density approach range based onmoisture-density-energy relationships. The method may includedetermining the asymptotic energy-density approach range based on two ormore of the site-specific results of the following field conditioncombinations: soil type, soil properties, compactor type, liftthickness, moisture content, and soil amendment; and correlating thedata by plotting or equivalent computational means to provide themaximum compaction conditions. All methods may be computerized.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

“ASTM” means American Society for Testing Materials.“AASHTO” means American Association of State Highway and TransportationOfficials“Asymptotic Energy-Density Approach” means a segment or range of rollerpasses wherein the incremental change in rolling resistance andcorresponding soil densification begins to be insignificant withsuccessive roller passes, thus representing full lift compaction, fulllift compaction performance, the end point of lift compaction, or the“design energy level” of lift compaction. Full lift compactionperformance is the compacted lift properties at full lift compactionincluding moisture-density relations and all physical/engineeringproperties. The term “Asymptotic Compaction Performance” isinterchangeable with “Asymptotic Energy-Density Approach.”“Asymptotic Compaction Performance” means lift compaction performance inthe “Asymptotic Energy-Density Approach” range.“Best fit curve” means the curve plotted through a set of data pointsthat best fits the data trends and variations by methods of bilinear orcurvilinear approximation or averaging, and educated visualextrapolations.“Compaction Energy” means the energy component that is transferred by acompactor or compaction roller into the ground or soil lift over whichit is traveling, and represents the energy that causes soildensification. The term can also be defined as the compaction energyrequired to overcome rolling resistance. The term “compactive energy” isinterchangeable with “compaction energy.”“Cumulative Compaction Energy” means the cumulation of Compaction Energywith each compactor pass.“Cumulative Average Rolling Resistance” means the cumulative RollingResistance of a compactor rolling or driving over a soil lift thatcumulates with each consecutive compactor pass until completion.“Design Energy Level” means a cumulative compaction energy levelrepresenting, equating to or equaling the actual cumulative fieldenergies at asymptotic compaction performance produced bycompactor-soil-moisture-lift thickness-soil amendment combinations, at aselect point within the asymptotic energy-density approach inconstruction and at a select percent-density sector on the sitelift-specific M-D curve. Design energy level may be used in a controlledenvironment, in field or lab testing, and in engineering uses includinglaboratory compaction testing.“Rolling resistance” is defined as the resistance to the compactorrolling or driving over the soil lift being compacted. The term can alsobe defined as the rimpull performance, energy or power of the compactorrequired to overcome resistance to compactor rolling. The term can alsobe defined as the fraction of rimpull energy or compactor drive energyneeded to overcome energy loss into the earthen lift being compacted.“Soil Type” is defined as an earthen soil material defined orcharacterized by its physical properties, index properties orengineering properties, and/or classification in engineeringclassification systems (i.e., Unified Soil Classification System,AASHTO, etc.). The definition also includes soils mixed with amendments,reagents, additives or other materials which are designed to alter orimprove its physical properties, index properties or engineeringproperties for improved or altered compaction efficiencies or compactedproperties.

General Description of the Invention

The inventors recognized that compaction energy transferred from awheel-ground system is a function of rolling resistance and that rollingresistance is a function of the compactor's rimpull energy or driveenergy. The rimpull energy of a given roller wheel is considered to be amore suitable parameter for determination of field compaction energythan the compactor's drawbar pull parameter as used by R. R. Proctor inthe development of standard methods.

The invention encompasses new and different methods for measuring,monitoring and/or determining actual, cumulative field compaction energyand compaction performance based on rolling resistance measurements. Theinvention includes a method for construction based on measuring,monitoring and/or determining actual, cumulative field compaction energyand associated engineering property relationships for a given soil type,the improvement that comprises for a selected compactor, determining theenergy transferred to the soil by measuring field combination-specificrolling resistance as a function of rimpull energy or drive energyperformance, measuring, monitoring and/or plotting the variation ofrolling resistance, compaction energy or soil densification or both, fora given soil moisture content for a plurality of roller passes,determining the combination-specific, asymptotic energy-density approachrange, and thus determining when the earthwork design requirement is metor exceeded. The invention includes the correlation of engineeringproperties of compacted soil lifts to the actual cumulative compactionenergy levels and lift-specific combinations in construction, as opposedto fixed energy levels and standard practices.

EXAMPLE 1

At a construction site the rolling resistance of a wheel/ground systemsuitable for earthen fill construction is measured for a site-specificmoisture content, dry density, soil amendments, on successive rollerpasses and the changes in rolling resistance are monitored. Earthworkcompactors are used and each compactor's performance parameters andspecifications are recorded. Soil compaction is continued until changesin field compaction measurements are clearly in an asymptotic state andthe novel asymptotic compaction performance, a design energy level, orspecified target compacted density property or set of properties isachieved.

EXAMPLE 2

The invention includes a method for computation of the novel cumulativeaverage rolling resistance or asymptotic compaction performance for eachconstruction lift combination from the novel asymptotic energy-densityapproach formed by compaction performance measurement or quantificationwith each compactor pass to and within the novel asymptoticenergy-density approach range. This is accomplished as follows:

For each lift-specific pass, compactor rolling resistance and soildensification may be measured by cumulative rimpull energy performance,or drive train energy or power, compactor energy distribution or powertransmission, or performance engine horsepower or other means formeasuring resulting rimpull energy and compaction energy transfer to thesoil; and the rolling resistance variance with roller passes iscomputed. The cumulative averages are made with values taken from thefirst compactor pass up to the select pass at or within the novelasymptotic energy-density approach. The cumulative averages representingvalues at the novel asymptotic energy approach can then be used forcomputing unit cumulative compaction energy per unit lift volume. Theinvention provides a novel tool that reduces problems in meeting designrequirements and specifications and provides novel quality controlduring construction.

We claim:
 1. A method for construction of earthen fills that comprisesuse of actual, cumulative field compaction energy generated by soilcompactors as a function of rolling resistance with soil densification,to determine an asymptotic energy-density approach range and associatedasymptotic compaction performance.
 2. The method of claim 1 that tiesthe asymptotic compaction performance to any value selected from thegroup consisting of moisture-density relations, optimummoisture-density, percentages of maximum dry-density compaction, soilproperties, compacted soil properties, compactor performance,compactor-soil interface, and end point of lift compaction.
 3. Themethod of claim 1 wherein any drive train step is measured to establishchange in rimpull rolling resistance.
 4. The method of claim 1 whereinrimpull rolling resistance is measured by compactor power performance.5. The method of claim 1 wherein compaction is deemed complete when thechange in rolling resistance falls below a value consideredinsignificant.
 6. The method of claim 5 wherein compaction is deemedcomplete when the measured change in rolling resistance is less than themeasured error for determining rolling resistance.
 7. The method ofclaim 1 where change in a component of engine power is measured andtransmitted to a computation means to track variation of engine powerfor each pass over a given area to be compacted, and the compactoroperator receives an instruction when the desired magnitude of thechange in engine power is achieved.
 8. The method of claim 1 wherein areal time computation of change in rimpull rolling resistance is used toidentify an asymptotic energy-density approach range.
 9. The method ofclaim 1 wherein drive power data from the compactor is transmitted to areceiving station and the transmitted drive power data is used tocompute an asymptotic energy density approach range.
 10. A method forconstruction of earthen fills that comprises determining field specificrolling resistance at the asymptotic energy-density approach andcorrelating the determined rolling resistance to engineering propertiesof the compacted lift.
 11. The method of claim 10 that correlates theasymptotic compaction performance to one or more values selected fromthe group consisting of moisture-density relations, optimummoisture-density, percentages of maximum dry-density compaction, soilproperties, compactor performance, compactor-soil interface, and the endpoint of lift compaction.
 12. The method of claim 10 wherein compactorengine horsepower is measured to establish change in rolling resistance.13. The method of claim 10 wherein rimpull rolling resistance ismeasured by compactor power performance.
 14. The method of claim 10wherein compaction is deemed complete when the change in rollingresistance falls below a value considered insignificant.
 15. The methodof claim 14 wherein compaction is deemed complete when the measuredchange in rolling resistance is less than the measured error fordetermining rolling resistance.
 16. The method of claim 10 where changein engine power is measured and transmitted to a computation means totrack variation of engine power for each pass over a given area to becompacted, and the compactor operator receives an instruction when thedesired magnitude of the change in engine power is achieved.
 17. Themethod of claim 10 wherein a real time computation of change in rollingresistance is used to identify the asymptotic energy-density approachrange.
 18. The method of claim 10 wherein engine drive train power datafrom the compactor is transmitted to a receiving station and thetransmitted engine drive power data is used to compute the asymptoticenergy density approach range.
 19. A method for compaction of earthenfills that comprises determining field measured, site specific rimpullrolling resistance changes until the magnitude of change in rimpullrolling resistance indicates the asymptotic energy-density approachrange has been reached for the area being compacted.
 20. The method ofclaim 19 wherein changes in rimpull rolling resistance are measured bychanges in compactor power performance.